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Verifying Visibility-Based Weak Consistency [article]

Siddharth Krishna, Michael Emmi, Constantin Enea, Dejan Jovanovic
2019 arXiv   pre-print
Multithreaded programs generally leverage efficient and thread-safe concurrent objects like sets, key-value maps, and queues. While some concurrent-object operations are designed to behave atomically, each witnessing the atomic effects of predecessors in a linearization order, others forego such strong consistency to avoid complex control and synchronization bottlenecks. For example, contains (value) methods of key-value maps may iterate through key-value entries without blocking concurrent
more » ... tes, to avoid unwanted performance bottlenecks, and consequently overlook the effects of some linearization-order predecessors. While such weakly-consistent operations may not be atomic, they still offer guarantees, e.g., only observing values that have been present. In this work we develop a methodology for proving that concurrent object implementations adhere to weak-consistency specifications. In particular, we consider (forward) simulation-based proofs of implementations against relaxed-visibility specifications, which allow designated operations to overlook some of their linearization-order predecessors, i.e., behaving as if they never occurred. Besides annotating implementation code to identify linearization points, i.e., points at which operations' logical effects occur, we also annotate code to identify visible operations, i.e., operations whose effects are observed; in practice this annotation can be done automatically by tracking the writers to each accessed memory location. We formalize our methodology over a general notion of transition systems, agnostic to any particular programming language or memory model, and demonstrate its application, using automated theorem provers, by verifying models of Java concurrent object implementations.
arXiv:1911.01508v1 fatcat:xeu4aoa4szbupchvodlzcaoyay

Online testing of federated and heterogeneous distributed systems

Marco Canini, Vojin Jovanović, Daniele Venzano, Dejan Novaković, Dejan Kostić
2011 Computer communication review  
DiCE is a system for online testing of federated and heterogeneous distributed systems. We have built a prototype of DiCE and integrated it with an open-source BGP router. DiCE quickly detects three important classes of faults, resulting from configuration mistakes, policy conflicts and programming errors. The goal of this demo is to showcase our DiCE prototype while it executes an experiment that involves exploring BGP system behavior in a topology with 27 BGP routers and Internet-like conditions (Figure 1 ).
doi:10.1145/2043164.2018507 fatcat:jfqmkjcyqfg5pdfdxrcwbpndsa

Polite Theories Revisited [chapter]

Dejan Jovanović, Clark Barrett
2010 Lecture Notes in Computer Science  
The classic method of Nelson and Oppen for combining decision procedures requires the theories to be stably-infinite. Unfortunately, some important theories do not fall into this category (e.g. the theory of bit-vectors). To remedy this problem, previous work introduced the notion of polite theories. Polite theories can be combined with any other theory using an extension of the Nelson-Oppen approach. In this paper we revisit the notion of polite theories, fixing a subtle flaw in the original
more » ... finition. We give a new combination theorem which specifies the degree to which politeness is preserved when combining polite theories. We also give conditions under which politeness is preserved when instantiating theories by identifying two sorts. These results lead to a more general variant of the theorem for combining multiple polite theories. * This work was funded in part by SRC contract 2008-TJ-1850. 1 smaller (infinite) model via the Löwenheim-Skolem theorem in first-order logic. Most commonlyused theories can be represented in this framework and are shown to be flexible. Reasoning about cardinality also plays a major role in this approach-a solver for a parametric theory (called a strong solver) is required to process not only the formula being checked, but also a set of cardinality constraints over the domain sizes. Although this direction is promising, particularly because of the advantages of parametricity, the approach as developed thus far would be cumbersome to implement in a practical system. In particular, while reasoning about cardinalities is possible for a wide class of important theories, it can be computationally expensive, and theory decision procedures are typically not designed with this additional requirement in mind. An alternative approach uses the notion of polite theories introduced in [7]. Polite theories can also be combined with an arbitrary other theory. However, this approach does not require the computation of the mincard function. Instead, a decision procedure for a polite theory must be able to generate explicitly a witness formula that enumerates any required domain elements using additional variables. The authors show that many commonly-used theories are polite (including theories of lists, arrays, sets, and multi-sets). This approach seems more practical than those that require reasoning about cardinalities explicitly. And, while proving that a theory is polite can be difficult and needs to be done on a per-theory basis, once this is done, the combination method can be easily implemented. In this paper, we revisit and extend the results on polite theories from [7] . Section 2 gives definitions and background on many-sorted logic and theory combination. Section 3 begins by introducing polite theories, making a small but needed modification to the definition of finite witnessability (one of the two properties that make up politeness), and then goes on to show that when combining polite theories, the resulting theory is also polite (with respect to a possibly reduced set of sorts). Section 5 addresses theory instantiation, the construction of a new theory by identifying two sorts in an existing theory; we prove that instantiation preserves politeness. Finally, Section 4 discusses the combination of multiple polite theories, culminating in a combination result that is more general than the ones presented in [7] .
doi:10.1007/978-3-642-16242-8_29 fatcat:ze2kux6fwnfsnlje24wh4rqm34

Communication Technologies, Covid-19 and Core-Competence of the Tourism Enterprises

Jelena Premović, Slavoljub Vujović, Dijana Jovanović, Dejan Jovanović
2021 Ecologica  
Having in mind the growing importance and role that ICT have in improving the quality of the tourist offer, it is very important that employees in the tourism industry constantly monitor the trends of change in this area and to continuously train and improve in this technological sphere. The aim of research is to point out the importance and possibilities of applying information and communication technologies (ICT) in tourism enterprises as a factor in improving quality the tourist offer.
more » ... k: Imajući u vidu sve veći značaj i ulogu koju IKT imaju u poboljšanju kvaliteta turističke ponude, veoma je važno da zaposleni u turističkoj industriji neprestano prate trendove promena u ovoj oblasti i da kontinuirano treniraju i usavršavaju se u ovoj tehnološkoj sferi. Cilj istraživanja je da se ukaže na značaj i mogućnosti primene informaciono-komunikacionih tehnologija (IKT) u turističkim preduzećima kao faktora za poboljšanje kvaliteta turističke ponude. Ključne reči: informacione i komunikacione tehnologije, turistička ponuda, preduzeća, ljudski resursi.
doi:10.18485/ecologica.2021.28.102.9 fatcat:io7aznufg5ckxm52zk35qtw2oy


Dimitrijević Jovanović, Predrag (Miodrag) Zivkovic, Jelena Janevski, Mica Vukic, Ana Momcilovic, Dejan Jovanovic
2019 Ekologìčna bezpeka ta zbalansovane resursokoristuvannâ  
Integration of nature, live, organic materials, in the design of built areas and building structure is an architectural response to environmental problems of dense urban areas. At the site where green space is limited, greening the building envelope is the solution for the issues such as heat waves, flooding, and noise and air pollution. The benefits could be predicted only using accurate simulation model of this technology. The energy balance of green living roof was researched through models
more » ... eveloped over the years by various authors. Most models have been developed and validated with data from extensive roofs and more than 50% of the models were validated using data from warm temperate climatic zones. Ability to determine the impact of green living roofs at different stages of their architectural design process is of most importance if the incorporation this technology is planned due to the impact on building and urban level.
doi:10.31471/2415-3184-2019-1(19)-104-110 fatcat:zqzro2r7t5akxggaop6egbsz34

Electrocortical (EEG) correlates of music and states of consciousness

Lazar Skaric, Milorad Tomasevic, Dejan Rakovic, Emil Jovanov, Vlada Radivojevic, Predrag Sukovic, Marko Car, Dejan Radenovic
2007 Neuropsychological Trends  
The study of the perception of music is a paramount example of multidisciplinary research. In spite of a lot of theoretical and experimental efforts to understand musical processing, attempts to localize musical abilities in particular brain regions were largely unsuccessful, save for the difference between musicians and non musicians, especially in hemispheric specialization and in EEG correlational dimensions. Having in mind that human emotional response to music and to art in general is
more » ... c dependent, this motivated us to address our question to a similar possible neurobiological origin of musicogenic altered states of consciousness and its possible EEG correlates, "resonantly" induced by deep spiritual music. For example, as in sound-induced altered states of consciousness cultivated in some Eastern yogic practices. The musicogenic states of consciousness are evaluated within a group of 6 adults, upon the influence of 4 types of spiritual music. The most prominent changes in theta or alpha frequency bands were induced in two subjects, upon the influence of Indian spiritual music, Bhajan.
doaj:389485b188cb41f69dbd9dee8b3b8f07 fatcat:4gkcxosyebg2leku6fa7smx27i

HCV Infection and Chronic Renal Disease

Sofija Sekulic, Zeljko Mijailovic, Dejan Petrovic, Ruzica Lukic, Marina Jovanovic, Ivan Jovanovic
2021 Serbian Journal of Experimental and Clinical Research  
Chronic Hepatitis C virus (HCV) infection is defined as persistence of HCV RNA in the blood for more than six months. HCV is a major cause of chronic liver disease and cirrhosis. It's serious public health problem, affects about 71 million people worldwide. HCV doesn't destroy hepatocytes directly. It activates the host's innate and acquired immune system and causes liver injury indirectly. Behind hepatic, HCV can cause extra-hepatic manifestations. One of them is renal disease which can lead
more » ... end-stage renal disease, ESRD. The prevalence of HCV infection in patients on hemodialysis is high, ranging from 5% to 60%. HCV infection is a significant cause of morbidity and mortality in patients with ESRD on hemodialysis. In this review, we discuss HCV infection and chronic renal disease as comorbidities, their severity and outcome.
doi:10.2478/sjecr-2021-0010 fatcat:2p4nfbtrizdpvd3frtnonoaosa

Solving Non-linear Arithmetic [chapter]

Dejan Jovanović, Leonardo de Moura
2012 Lecture Notes in Computer Science  
1299 iSAT 203 122 291 16 21 24 20 822 0 0 535 986 cvc3 150 13 361 5 12 3 0 0 0 0 523 22 MiniSmt 40 697 35 0 46 1370 0 0 18 44 139 2112 The website  ... 
doi:10.1007/978-3-642-31365-3_27 fatcat:gvxeacvwcberxicm2boayamtdi

Formal Specification and Verification of Solidity Contracts with Events [article]

Ákos Hajdu, Dejan Jovanović, Gabriela Ciocarlie
2020 arXiv   pre-print
Events in the Solidity language provide a means of communication between the on-chain services of decentralized applications and the users of those services. Events are commonly used as an abstraction of contract execution that is relevant from the users' perspective. Users must, therefore, be able to understand the meaning and trust the validity of the emitted events. This paper presents a source-level approach for the formal specification and verification of Solidity contracts with the
more » ... focus on events. Our approach allows specification of events in terms of the on-chain data that they track, and predicates that define the correspondence between the blockchain state and the abstract view provided by the events. The approach is implemented in solc-verify, a modular verifier for Solidity, and we demonstrate its applicability with various examples.
arXiv:2005.10382v1 fatcat:bzir34kmvvfrpaauxwnipcxzme

Slobodan Jovanovic and Serbian-Russian relations in the context of international public law

Dejan Mirovic
2018 Zbornik Matice srpske za drustvene nauke  
Уни вер зи тет у При шти ни -Ко сов ска Ми тро ви ца Прав ни фа кул тет Ло ле Ри ба ра 29, Ко сов ска Ми тро ви ца, Ср би ја de jan.mi ro vic .rs СА ЖЕ ТАК: Сло бо дан Јо ва но вић, је дан од нај ве ћих срп ских прав ни ка, дао је по зи тив ну оце ну срп ско-ру ских од но са у кон тек сту ме ђу на род ног јав ног пра ва. Упр кос то ме што је у иде о ло шком сми слу био ан гло фил, он је у сво јим де ли ма ис ти цао да су Бу ку ре штан ски мир, Акер ман ска конвен ци ја и Је дрен ски мир
more » ... и ли би ла те рал ни уго во ри из ме ђу Ру си је и Турске, с од ред ба ма ко је су ишле у ко рист тре ћих (pac tum in fa vo rem tre tii), тј. Ср би је. Он је дао по зи тив ну оце ну и ру ској ди пло ма ти ји 19. ве ка. КЉУЧ НЕ РЕ ЧИ: Ру си ја, Ср би ја, Сло бо дан Јо ва но вић, ме ђу на род но јав но пра во, ди пло ма ти ја, Бу ку ре штан ски мир, Акер ман ска кон вен ци ја, Је дрен ски мир
doi:10.2298/zmsdn1868743m fatcat:h4a2vpatcrbcphxlc2hv2q4iu4

Logical Analysis of Hash Functions [chapter]

Dejan Jovanović, Predrag Janičić
2005 Lecture Notes in Computer Science  
Jovanović and P. Janičić 10000 1000 1 round 1 round 1000 2 rounds 3 rounds 100 2 rounds 3 rounds 4 rounds 4 rounds 100 10 10 1 1 0.1 0.1 0.01 0.01 2 4 6 8 10 12 14 16 2 4 6 8 10 12 Fig. 4.  ... 
doi:10.1007/11559306_11 fatcat:jgqmmw4qtzcjzapnqa6t2mpfwq

Low-cost teslameter based on hall effect sensor MLX90242

Ugljesa Jovanovic, Igor Jovanovic, Marjan Blagojevic, Dejan Krstic, Dragan Mancic
2018 Serbian Journal of Electrical Engineering  
A low-cost teslameter based on a Hall effect sensor MLX90242 is proposed in this paper. The proposed teslameter is built around a PIC18F4550 microcontroller and it can measure magnetic flux density in the range between -55 mT and 55 mT. Temperature stability of measurements originates from the MLX90242 sensor itself. In order for the proposed transducer to be accurate, it has undergone a calibration procedure using a highly accurate teslameter employed as reference instruments and high-quality
more » ... ariable-field electromagnet. The proposed teslameter can store measurements on a PC via built-in USB communication.
doi:10.2298/sjee1802225j fatcat:v67ovcrjizds3akmhivrcawby4

Following the Principles of Ergonomics and Musculoskeletal Disorders in Ultrasonographers

Vanja Jovanovic, Jelena Maric, Dejan Jovanovic
2020 Serbian Journal of Experimental and Clinical Research  
AbstractBackground/Aim. It has been noticed that doctors who regularly perform ultrasound examinations have different clinical manifestations of musculoskeletal disorders. The aim of this research is to examine the level of knowledge of ultrasonographers regarding preventative measures and health consequences of the forced body positions during work.Subjects and methods. The total of 75 doctors of both genders, aged 31-50 years, who use ultrasound diagnostics participated in the research. The
more » ... search was conducted throughout 2016, as a cross-sectional study, with the aid of a structured questionaire.Results. The total of 60% subjects either rarely use the break during working hours or do not have a break at all. The participants most commonly use the movable monitor and the ability to wrap the cable around their arm (73,3%). This percentage is similar in all age groups. The respondents most often stated that they walk daily (41,3%), with no differences among age groups. 25% of the respondents negate any spine related pains, while over a half said that they experience pain in one segment of the spinal column (cervical, thoracic or lumbar), regardless of the age group. 52% said that they serch for information on their own accord, while 36% stated that they are not at all informed. Only in less than 10% of cases is information provided by the authorities in the institution where the participants are employed, and during regular health examinations, information is given by the designated doctor in 2,7% of cases.Conclusion. The respondents implement the recommendations regarding safe work and other preventative measures to a very small extent, regardless of gender and age. Most of the respondents experience pain in the spine and joints, which can be related to the work in ultrasound diagnostics. Additionally, doctors are not well-informed regarding the preventative measures.
doi:10.2478/sjecr-2020-0036 fatcat:xxxke7rg2vgzhk2gecyl33ugny

A Model-Constructing Satisfiability Calculus [chapter]

Leonardo de Moura, Dejan Jovanović
2013 Lecture Notes in Computer Science  
We present a new calculus where recent model-based decision procedures and techniques can be justified and combined with the standard DPLL(T) approach to satisfiability modulo theories. The new calculus generalizes the ideas found in CDCL-style propositional SAT solvers to the first-order setting.
doi:10.1007/978-3-642-35873-9_1 fatcat:lg2s3dcubzgenaxgful47e373q

Cutting to the Chase

Dejan Jovanović, Leonardo de Moura
2013 Journal of automated reasoning  
We describe a new algorithm for solving linear integer programming problems. The algorithm performs a DPLL style search for a feasible assignment, while using a novel cut procedure to guide the search away from the conflicting states.
doi:10.1007/s10817-013-9281-x fatcat:sern2saixzcytkstfvolixh3eu
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